/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.core;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.comet.CometEvent;
import org.apache.catalina.comet.CometProcessor;
import org.apache.catalina.connector.ClientAbortException;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.valves.ValveBase;
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.log.SystemLogHandler;
import org.apache.tomcat.util.res.StringManager;

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Valve that implements the default basic behavior for the
 * <code>StandardWrapper</code> container implementation.
 *
 * @author Craig R. McClanahan
 */
final class StandardWrapperValve
		extends ValveBase {

	/**
	 * The string manager for this package.
	 */
	private static final StringManager sm =
			StringManager.getManager(Constants.Package);

	// ----------------------------------------------------- Instance Variables
	// Some JMX statistics. This valve is associated with a StandardWrapper.
	// We expose the StandardWrapper as JMX ( j2eeType=Servlet ). The fields
	// are here for performance.
	private volatile long processingTime;
	private volatile long maxTime;
	private volatile long minTime = Long.MAX_VALUE;
	private volatile int requestCount;
	private volatile int errorCount;

	//------------------------------------------------------ Constructor
	public StandardWrapperValve() {
		super(true);
	}


	// --------------------------------------------------------- Public Methods

	/**
	 * Invoke the servlet we are managing, respecting the rules regarding
	 * servlet lifecycle and SingleThreadModel support.
	 *
	 * @param request  Request to be processed
	 * @param response Response to be produced
	 * @throws IOException      if an input/output error occurred
	 * @throws ServletException if a servlet error occurred
	 */
	@Override
	public final void invoke(Request request, Response response)
			throws IOException, ServletException {

		// Initialize local variables we may need
		boolean unavailable = false;
		Throwable throwable = null;
		// This should be a Request attribute...
		long t1 = System.currentTimeMillis();
		requestCount++;
		StandardWrapper wrapper = (StandardWrapper) getContainer();
		Servlet servlet = null;
		Context context = (Context) wrapper.getParent();

		// Check for the application being marked unavailable
		if (!context.getState().isAvailable()) {
			response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
					sm.getString("standardContext.isUnavailable"));
			unavailable = true;
		}

		// Check for the servlet being marked unavailable
		if (!unavailable && wrapper.isUnavailable()) {
			container.getLogger().info(sm.getString("standardWrapper.isUnavailable",
					wrapper.getName()));
			long available = wrapper.getAvailable();
			if ((available > 0L) && (available < Long.MAX_VALUE)) {
				response.setDateHeader("Retry-After", available);
				response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
						sm.getString("standardWrapper.isUnavailable",
								wrapper.getName()));
			} else if (available == Long.MAX_VALUE) {
				response.sendError(HttpServletResponse.SC_NOT_FOUND,
						sm.getString("standardWrapper.notFound",
								wrapper.getName()));
			}
			unavailable = true;
		}

		// Allocate a servlet instance to process this request
		try {
			if (!unavailable) {
				servlet = wrapper.allocate();
			}
		} catch (UnavailableException e) {
			container.getLogger().error(
					sm.getString("standardWrapper.allocateException",
							wrapper.getName()), e);
			long available = wrapper.getAvailable();
			if ((available > 0L) && (available < Long.MAX_VALUE)) {
				response.setDateHeader("Retry-After", available);
				response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
						sm.getString("standardWrapper.isUnavailable",
								wrapper.getName()));
			} else if (available == Long.MAX_VALUE) {
				response.sendError(HttpServletResponse.SC_NOT_FOUND,
						sm.getString("standardWrapper.notFound",
								wrapper.getName()));
			}
		} catch (ServletException e) {
			container.getLogger().error(sm.getString("standardWrapper.allocateException",
					wrapper.getName()), StandardWrapper.getRootCause(e));
			throwable = e;
			exception(request, response, e);
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.allocateException",
					wrapper.getName()), e);
			throwable = e;
			exception(request, response, e);
			servlet = null;
		}

		// Identify if the request is Comet related now that the servlet has been allocated
		boolean comet = false;
		if (servlet instanceof CometProcessor && Boolean.TRUE.equals(request.getAttribute(
				Globals.COMET_SUPPORTED_ATTR))) {
			comet = true;
			request.setComet(true);
		}

		MessageBytes requestPathMB = request.getRequestPathMB();
		DispatcherType dispatcherType = DispatcherType.REQUEST;
		if (request.getDispatcherType() == DispatcherType.ASYNC) dispatcherType = DispatcherType.ASYNC;
		request.setAttribute(Globals.DISPATCHER_TYPE_ATTR, dispatcherType);
		request.setAttribute(Globals.DISPATCHER_REQUEST_PATH_ATTR,
				requestPathMB);
		// Create the filter chain for this request
		ApplicationFilterFactory factory =
				ApplicationFilterFactory.getInstance();
		ApplicationFilterChain filterChain =
				factory.createFilterChain(request, wrapper, servlet);

		// Reset comet flag value after creating the filter chain
		request.setComet(false);

		// Call the filter chain for this request
		// NOTE: This also calls the servlet's service() method
		try {
			if ((servlet != null) && (filterChain != null)) {
				// Swallow output if needed
				if (context.getSwallowOutput()) {
					try {
						SystemLogHandler.startCapture();
						if (request.isAsyncDispatching()) {
							request.getAsyncContextInternal().doInternalDispatch();
						} else if (comet) {
							filterChain.doFilterEvent(request.getEvent());
							request.setComet(true);
						} else {
							filterChain.doFilter(request.getRequest(),
									response.getResponse());
						}
					} finally {
						String log = SystemLogHandler.stopCapture();
						if (log != null && log.length() > 0) {
							context.getLogger().info(log);
						}
					}
				} else {
					if (request.isAsyncDispatching()) {
						request.getAsyncContextInternal().doInternalDispatch();
					} else if (comet) {
						request.setComet(true);
						filterChain.doFilterEvent(request.getEvent());
					} else {
						filterChain.doFilter
								(request.getRequest(), response.getResponse());
					}
				}

			}
		} catch (ClientAbortException e) {
			throwable = e;
			exception(request, response, e);
		} catch (IOException e) {
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			throwable = e;
			exception(request, response, e);
		} catch (UnavailableException e) {
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			//            throwable = e;
			//            exception(request, response, e);
			wrapper.unavailable(e);
			long available = wrapper.getAvailable();
			if ((available > 0L) && (available < Long.MAX_VALUE)) {
				response.setDateHeader("Retry-After", available);
				response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
						sm.getString("standardWrapper.isUnavailable",
								wrapper.getName()));
			} else if (available == Long.MAX_VALUE) {
				response.sendError(HttpServletResponse.SC_NOT_FOUND,
						sm.getString("standardWrapper.notFound",
								wrapper.getName()));
			}
			// Do not save exception in 'throwable', because we
			// do not want to do exception(request, response, e) processing
		} catch (ServletException e) {
			Throwable rootCause = StandardWrapper.getRootCause(e);
			if (!(rootCause instanceof ClientAbortException)) {
				container.getLogger().error(sm.getString(
						"standardWrapper.serviceExceptionRoot",
						wrapper.getName(), context.getName(), e.getMessage()),
						rootCause);
			}
			throwable = e;
			exception(request, response, e);
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			throwable = e;
			exception(request, response, e);
		}

		// Release the filter chain (if any) for this request
		if (filterChain != null) {
			if (request.isComet()) {
				// If this is a Comet request, then the same chain will be used for the
				// processing of all subsequent events.
				filterChain.reuse();
			} else {
				filterChain.release();
			}
		}

		// Deallocate the allocated servlet instance
		try {
			if (servlet != null) {
				wrapper.deallocate(servlet);
			}
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.deallocateException",
					wrapper.getName()), e);
			if (throwable == null) {
				throwable = e;
				exception(request, response, e);
			}
		}

		// If this servlet has been marked permanently unavailable,
		// unload it and release this instance
		try {
			if ((servlet != null) &&
					(wrapper.getAvailable() == Long.MAX_VALUE)) {
				wrapper.unload();
			}
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.unloadException",
					wrapper.getName()), e);
			if (throwable == null) {
				throwable = e;
				exception(request, response, e);
			}
		}
		long t2 = System.currentTimeMillis();

		long time = t2 - t1;
		processingTime += time;
		if (time > maxTime) maxTime = time;
		if (time < minTime) minTime = time;

	}

	/**
	 * Process a Comet event. The main differences here are to not use sendError
	 * (the response is committed), to avoid creating a new filter chain
	 * (which would work but be pointless), and a few very minor tweaks.
	 *
	 * @param request  The servlet request to be processed
	 * @param response The servlet response to be created
	 * @throws IOException      if an input/output error occurs, or is thrown
	 *                          by a subsequently invoked Valve, Filter, or Servlet
	 * @throws ServletException if a servlet error occurs, or is thrown
	 *                          by a subsequently invoked Valve, Filter, or Servlet
	 */
	@Override
	public void event(Request request, Response response, CometEvent event)
			throws IOException, ServletException {

		// Initialize local variables we may need
		Throwable throwable = null;
		// This should be a Request attribute...
		long t1 = System.currentTimeMillis();
		// FIXME: Add a flag to count the total amount of events processed ? requestCount++;

		StandardWrapper wrapper = (StandardWrapper) getContainer();
		if (wrapper == null) {
			// Context has been shutdown. Nothing to do here.
			return;
		}

		Servlet servlet = null;
		Context context = (Context) wrapper.getParent();

		// Check for the application being marked unavailable
		boolean unavailable = !context.getState().isAvailable() ||
				wrapper.isUnavailable();

		// Allocate a servlet instance to process this request
		try {
			if (!unavailable) {
				servlet = wrapper.allocate();
			}
		} catch (UnavailableException e) {
			// The response is already committed, so it's not possible to do anything
		} catch (ServletException e) {
			container.getLogger().error(sm.getString("standardWrapper.allocateException",
					wrapper.getName()), StandardWrapper.getRootCause(e));
			throwable = e;
			exception(request, response, e);
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.allocateException",
					wrapper.getName()), e);
			throwable = e;
			exception(request, response, e);
			servlet = null;
		}

		MessageBytes requestPathMB = request.getRequestPathMB();
		request.setAttribute(Globals.DISPATCHER_TYPE_ATTR,
				DispatcherType.REQUEST);
		request.setAttribute(Globals.DISPATCHER_REQUEST_PATH_ATTR,
				requestPathMB);
		// Get the current (unchanged) filter chain for this request
		ApplicationFilterChain filterChain =
				(ApplicationFilterChain) request.getFilterChain();

		// Call the filter chain for this request
		// NOTE: This also calls the servlet's event() method
		try {
			if ((servlet != null) && (filterChain != null)) {

				// Swallow output if needed
				if (context.getSwallowOutput()) {
					try {
						SystemLogHandler.startCapture();
						filterChain.doFilterEvent(request.getEvent());
					} finally {
						String log = SystemLogHandler.stopCapture();
						if (log != null && log.length() > 0) {
							context.getLogger().info(log);
						}
					}
				} else {
					filterChain.doFilterEvent(request.getEvent());
				}

			}
		} catch (ClientAbortException e) {
			throwable = e;
			exception(request, response, e);
		} catch (IOException e) {
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			throwable = e;
			exception(request, response, e);
		} catch (UnavailableException e) {
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			// Do not save exception in 'throwable', because we
			// do not want to do exception(request, response, e) processing
		} catch (ServletException e) {
			Throwable rootCause = StandardWrapper.getRootCause(e);
			if (!(rootCause instanceof ClientAbortException)) {
				container.getLogger().error(sm.getString(
						"standardWrapper.serviceExceptionRoot",
						wrapper.getName(), context.getName(), e.getMessage()),
						rootCause);
			}
			throwable = e;
			exception(request, response, e);
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString(
					"standardWrapper.serviceException", wrapper.getName(),
					context.getName()), e);
			throwable = e;
			exception(request, response, e);
		}

		// Release the filter chain (if any) for this request
		if (filterChain != null) {
			filterChain.reuse();
		}

		// Deallocate the allocated servlet instance
		try {
			if (servlet != null) {
				wrapper.deallocate(servlet);
			}
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.deallocateException",
					wrapper.getName()), e);
			if (throwable == null) {
				throwable = e;
				exception(request, response, e);
			}
		}

		// If this servlet has been marked permanently unavailable,
		// unload it and release this instance
		try {
			if ((servlet != null) &&
					(wrapper.getAvailable() == Long.MAX_VALUE)) {
				wrapper.unload();
			}
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			container.getLogger().error(sm.getString("standardWrapper.unloadException",
					wrapper.getName()), e);
			if (throwable == null) {
				throwable = e;
				exception(request, response, e);
			}
		}

		long t2 = System.currentTimeMillis();

		long time = t2 - t1;
		processingTime += time;
		if (time > maxTime) maxTime = time;
		if (time < minTime) minTime = time;

	}


	// -------------------------------------------------------- Private Methods

	/**
	 * Handle the specified ServletException encountered while processing
	 * the specified Request to produce the specified Response.  Any
	 * exceptions that occur during generation of the exception report are
	 * logged and swallowed.
	 *
	 * @param request   The request being processed
	 * @param response  The response being generated
	 * @param exception The exception that occurred (which possibly wraps
	 *                  a root cause exception
	 */
	private void exception(Request request, Response response,
	                       Throwable exception) {
		request.setAttribute(RequestDispatcher.ERROR_EXCEPTION, exception);
		response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
		response.setError();
	}

	public long getProcessingTime() {
		return processingTime;
	}

	/**
	 * Deprecated   unused
	 */
	@Deprecated
	public void setProcessingTime(long processingTime) {
		this.processingTime = processingTime;
	}

	public long getMaxTime() {
		return maxTime;
	}

	/**
	 * Deprecated   unused
	 */
	@Deprecated
	public void setMaxTime(long maxTime) {
		this.maxTime = maxTime;
	}

	public long getMinTime() {
		return minTime;
	}

	/**
	 * Deprecated   unused
	 */
	@Deprecated
	public void setMinTime(long minTime) {
		this.minTime = minTime;
	}

	public int getRequestCount() {
		return requestCount;
	}

	/**
	 * Deprecated   unused
	 */
	@Deprecated
	public void setRequestCount(int requestCount) {
		this.requestCount = requestCount;
	}

	public int getErrorCount() {
		return errorCount;
	}

	/**
	 * Deprecated   unused
	 */
	@Deprecated
	public void setErrorCount(int errorCount) {
		this.errorCount = errorCount;
	}

	public void incrementErrorCount() {
		errorCount++;
	}

	@Override
	protected void initInternal() throws LifecycleException {
		// NOOP - Don't register this Valve in JMX
	}
}
